A common trend in machine design, particularly in the office equipment industry, is to organize a machine on a modular basis, wherein certain distinct subsystems of the machine are bundled together into modules which can be readily removed from the machine and replaced with new modules of the same or similar type. A modular design facilitates great flexibility in the business relationship with the customer. By providing subsystems in discrete modules, also known as “customer replaceable units” or CRUs, visits from a service representative can be made very short, since all the representative has to do is remove and replace a defective module. Actual repair of the module may take place remotely at the service provider's premises. Further, some customers may wish to have the ability to buy modules “off the shelf,” such as from an equipment supply store. Indeed, it is possible that a customer may lease the machine and wish to buy a supply of modules as needed. Further, the use of modules, particularly for expendable supply units (e.g., copier and printer toner bottles) are conducive to recycling activities.
In order to facilitate a variety of business arrangements among manufacturers, service providers, and customers, it is known to provide these modules with electronically-readable memory devices, also known as “customer replaceable unit monitors” or CRUMs, which, when the module is installed in the machine, enable the machine to both read information from the CRUM and also write information to the CRUM. The information read from, or written to, the CRUM may be used by the machine to perform various functions. For example, U.S. Pat. No. 6,016,409 entitled “System For Managing User Modules in a Digital Printing Apparatus”, which is incorporated by reference herein in its entirety, describes various data that may be stored in a CRUM and various functions that may be performed using this data.
The use of CRUMs in a machine requires that the machine include a means for communicating data between the CRUMs and the control circuitry resident in the machine. This may be accomplished wirelessly. For example, U.S. Pat. No. 6,377,764 issued Apr. 23, 2003 and entitled “Method and Apparatus for Communication, Without A Solid Medium, Among Control Boards in a Printing Apparatus,” which is incorporated by reference herein in its entirety, describes a digital printing apparatus in which one or more modules has a board therein, which is able to communicate with another board within the apparatus by infrared or other wireless communication. In another example, U.S. Pat. No. 6,351,621 to Richards et al., describes a printer or copier having a removable module, such as a marking material supply module or a marking device module, that is provided with a CRUM. The non-volatile memory of the CRUM is accessed through a wireless interface, such as a radio frequency identification (RFID) system, which is also associated with the module. The memory can be accessed, through wireless means, either by the printer or copier itself or by an external device.
Wireless identification systems (e.g., RFID systems) typically include two sub-assemblies: a tag (also known as a transponder) and a reader (also known as an interrogator, transceiver, or coupler). The tag is typically attached to an object, and includes, among other components, an antenna and an integrated circuit (IC) device. Stored within the IC device is information related to the object to which the tag is attached. While this information usually includes identification data for the object, it may include other information related to, or used by, the object (e.g., tracking information, usage information, computer code, etc.). For example, the object may be a CRU and the tag may be a CRUM.
In operation, the antenna on the tag receives incoming data signals superimposed on a modulated carrier signal, which is provided by an antenna on the reader. In response to the incoming data signals, the tag superimposes data from the IC device onto the carrier signal by changing its own circuit impedance. In some tags, known as passive tags, the carrier signal is used to provide operating power for the tag. In other tags, known as active tags, at least some of the operating power for the tag is provided by a source other than the carrier signal (e.g., a battery).
The reader forms the interface between the tag and a host computer. The reader generally includes an integrated circuit chip and associated circuitry that allows it to communicate with both the tag and the host computer. Typically, there is a predefined command set used by the host computer to control the reader, which passes the commands to the tag via the modulated carrier signal. The reader generates the modulated carrier signal to transmit data to the tag, and receives data from the tag by detecting the loading effects of the tag on the carrier signal.
Any given tag and reader combination will communicate data over a limited distance. For example, an RFID system that conforms to International Standards Organization (ISO) Standard 14443-2B (13.56 mega-Hertz (MHz)) is ideal for communicating over distances of between 0 millimeters (mm) to 30 mm. If a system is designed to operate in the 10 mm to 20 mm range, it is unlikely this system will work in the 40 mm to 50 mm range. Problematically, it is unlikely that the designed communication range can be maintained at every desired point of access (e.g., during production, packaging, shipping, and installation). For example, when a CRU having an attached CRUM is packaged for shipping or storage, the distance between the CRUM within the package and a reader external to the package may be greater than the designed operating range. As a result, the CRUM must be removed from the package to place the reader close enough for data communication between the CRUM and reader.
The distance over which the tag and the reader can communicate can be increased by increasing the size of the antenna on the tag; however, smaller tags are more desirable because of cost and space considerations.